PETER DOCKRILL 6 MAR 2018
Above our heads, something is not right. Earth's magnetic field is in a state of dramatic weakening – and according to mind-boggling new research, this phenomenal disruption is part of a pattern lasting for over 1,000 years.

Earth's magnetic field doesn't just give us our north and south poles; it's also what protects us from solar winds and cosmic radiation – but this invisible force field is rapidly weakening, to the point scientists think it could actually flip, with our magnetic poles reversing.

As crazy as that sounds, this actually does happen over vast stretches of time. The last time it occurred was about 780,000 years ago, although it got close again around 40,000 years back.

When it takes place, it's not quick, with the polarity reversal slowly occurring over thousands of years.

Nobody knows for sure if another such flip is imminent, and one of the reasons for that is a lack of hard data.

The region that concerns scientists the most at the moment is called the South Atlantic Anomaly – a huge expanse of the field stretching from Chile to Zimbabwe. The field is so weak within the anomaly that it's hazardous for Earth's satellites to enter it, because the additional radiation it's letting through could disrupt their electronics.

"We've known for quite some time that the magnetic field has been changing, but we didn't really know if this was unusual for this region on a longer timescale, or whether it was normal," says physicist Vincent Hare from the University of Rochester in New York.

One of the reasons scientists don't know much about the magnetic history of this region of Earth is it lacks what's called archeomagnetic data – physical evidence of magnetism in Earth's past, preserved in archaeological relics from bygone ages.

One such bygone age belonged to a group of ancient Africans, who lived in the Limpopo River Valley – which borders Zimbabwe, South Africa, and Botswana: regions that fall within the South Atlantic Anomaly of today.